The present invention relates generally to thermographic monitoring of electrical equipment and, in particular, to a system allowing automatic in-cabinet thermographic monitoring.
Preventive and predictive maintenance strategies monitor equipment to avoid costly repair and lost production associated with unexpected equipment failures. Preventative maintenance institutes regularly scheduled monitoring of electrical equipment, component replacement, and minor repairs. Predictive maintenance uses monitored data to more accurately assess maintenance scheduling and equipment replacement.
Thermographic monitoring can be used with preventive and predictive maintenance and employs cameras that are sensitive in the far infrared region (typically 3-15 μm) to provide non-contact thermal measurement of surface temperatures of equipment. Particularly for electronic equipment, such thermographic images may provide advanced warning of equipment failure that would not otherwise be apparent. High temperatures may indicate, for example, high resistance electrical junctions, overvoltage or overcurrent, damaged insulation or damaged conductors that may ultimately lead to catastrophic failure. A thermographic image can be taken while the equipment is in operation with minimal operator risk. Further, a thermographic image can simultaneously measure multiple components allowing rapid monitoring of many potential failure points.
There are a number of limitations to thermographic imaging. First, the equipment is relatively expensive and requires a trained operator to perform inspections and analyze the images. Second, although the inspections do not require contact with equipment, they can expose the operator to the risks attendant to being near operating equipment, e.g. arc flash and explosions. These risks can be minimized to some extent by the provision of infrared transparent ports or openable shutters in the equipment cabinets allowing the operator to perform the inspection without opening the equipment housings. Finally, the thermographic monitoring is necessarily periodic and may miss rapidly developing equipment failures.
One method of providing substantially continuous monitoring of electrical equipment is the attachment of thermal sensors (such as thermocouples or solid-state devices) directly to various portions of the equipment to provide for real time thermal monitoring. Such instrumentation of equipment can be complex and expensive if multiple points are to be monitored and is generally impractical for custom installations. The wiring attendant to such monitoring presents additional risk of short-circuits within the cabinet.